But you are a chosen race, a royal priesthood, a holy nation, a people for his own possession. Peter is not speaking of a distant future. He describes what you are now: chosen, royal, holy, God's own.
Your worth is not determined by performance or others' opinions. It was determined when God chose you in Christ. You are royal, because you belong to the King.
When busyness drives you to prove your worth, you ignore what God has spoken. Rest grows from knowing who you are.